1. Field of the Invention
The present invention relates to a linear guide system with an integrally formed rack, in which the rack which constitutes part of a rack and pinion mechanism serving as a linear drive mechanism and a linear guide system serving as a linear guide mechanism are integrated with each other.
2. Related Background Art
Conventionally, a rack constituting a drive mechanism and a linear guide system serving as a guide mechanism are separately manufactured, and then assembled into the above-mentioned kind of integrally formed linear guide system which is used in a robot or other kinds of machines. As the separately manufactured mechanisms are assembled, however, good assembly precision is hard to obtain. Thus, the rack may bite excessively or rack clearance may become too large, thereby shortening the life of the rack and generating a noise. In order to solve these problems, a rack linear guide system is proposed in Japanese Utility Model Appln. Laid-Open No. 2-43519, in which rack teeth 4 are integrally formed on a surface of a guide rail on which grooves for rolling members are not formed, as shown in FIG. 4.
In the proposed system, however, holes for fixing bolts can not be formed at predetermined intervals over the overall length in the longitudinal direction, thereby causing the following problems.
1 When the guide rail 31 needs to be bolted to a machine base, or the like, the system can not be used.
2 When sliders 2 which engage with the guide rail 31 so that they can move relatively to the guide rail 31 are fixed in order to linearly drive the guide rail 31 with respect to the sliders 2, that is, when the guide rail 31 does not have to be fixed to the machine base, a hole B.sub.31 for a fixing bolt is required to fix a component to the movable guide rail. In this case, a surface 4A in which the hole for the fixing bolt is worked should be provided at an end of the rack teeth 4, whereby the rail becomes longer and manufacture thereof becomes more difficult. Thus, an increase in manufacturing costs will occur.
3 The rack teeth 4 engage with a pinion 12 with their faces set to the upside or the down side because of facility in designing the relation between the pinion with which the rack teeth 4 engage and a rotational drive mechanism of the pinion 12. Therefore, engagement of the rack teeth 4 with the pinion 12 has to be adjusted in the vertical direction, which is more difficult than the adjustment in the horizontal direction. In addition both the direction of the deflection of the rail caused by its self-weight and that of the vibration caused by movement of the rack engaging with the pinion 12 coincide with the vertical direction, thereby shortening the life of the rack, generating a noise, making positioning more difficult, and causing other problems.
Incidentally, a system in which a guide rail has rolling groove(s) for rolling members in one side surface and a rack integrally formed in the opposite side surface has been disclosed in Japanese Utility Model Appln. Laid-Open No. 59-103925. This system is, however, supposed to employ a pair of said guide rails, and its application is considerably limited. Thus such a system is different from the linear guide system of the present invention in which sliders straddle the guide rail so as to move relatively to the guide rail.